Human nutrition Banker

1. (a) Which enzyme begins the digestion of protein in the stomach?A amylaseB lipaseC maltaseD pepsin [1]

1. (a) State the substrate and the products of the enzyme lipase. [2]
2. (b) Name the organ that secretes lipase into the duodenum. [1]

Lipase is added to full-cream milk containing a few drops of an indicator that is pink above pH 8.3 and colourless below it. A little sodium carbonate solution is first added so the milk starts pink. The time taken for the pink colour to disappear is recorded at four temperatures.temperature / °C | time for pink colour to disappear / s15 | 42025 | 21035 | 11055 | 600

1. (a) Explain why the pink colour disappears. [2]
2. (b) State the temperature at which lipase was most active in these results. [1]
3. (c) Calculate the rate of reaction at 25 °C as 1000 ÷ time. Give your answer to one decimal place. [1]

1. (a) Which row shows the places where starch is digested and the product of amylase action?A mouth and stomach; glucoseB mouth and small intestine; maltoseC stomach and small intestine; maltoseD mouth and small intestine; glucose [1]

1. (a) Complete the passage using suitable words.Starch is broken down to ______ by the enzyme amylase. This sugar is then broken down to ______ by the enzyme ______, which is found on the membranes of the epithelium lining the small intestine. Proteins are broken down to ______ by proteases such as pepsin and ______. [5]

1. (a) A student mixes salivary amylase with starch solution at different pH values at 37 °C. A drop of the mixture is tested with iodine solution every 15 s until it no longer turns blue-black. The results are:pH | time for starch to disappear / s4 | 3006 | 757 | 608 | 10010 | 600The rate of reaction can be found as 1000 ÷ time. Calculate the rate at pH 7 and at pH 4. Give each answer to one decimal place. [2]
2. (b) State the optimum pH of this amylase from these results. [1]
3. (c) Explain why the starch takes 600 s to disappear at pH 10. [2]

A student fills a length of Visking (dialysis) tubing with a mixture of starch solution and amylase solution, ties both ends and places it in a boiling tube of distilled water at 37 °C. Every 10 minutes, samples of the water outside the tubing are tested with iodine solution and with Benedict's solution.time / min | iodine test on water outside | Benedict's test on water outside0 | orange-brown | blue10 | orange-brown | green20 | orange-brown | orange30 | orange-brown | brick red

1. (a) Explain the results of the Benedict's test. [3]
2. (b) Explain why the iodine test on the water outside stays orange-brown throughout. [1]
3. (c) Describe a suitable control for this experiment. [1]

1. (a) State two functions of the hydrochloric acid secreted in the stomach. [2]
2. (b) Pepsin stops working when the stomach contents reach the duodenum. Explain why. [3]

1. (a) Explain why proteins in a meal of chicken karahi must be digested before they can be used by body cells. [3]

1. (a) In some people with cystic fibrosis, thick mucus blocks the duct that carries pancreatic juice to the duodenum. Suggest and explain two effects of this on digestion. [4]

1. (a) What is the effect of bile on fats in the small intestine?A It breaks fats down into fatty acids and glycerol.B It emulsifies fats into small droplets.C It absorbs fats into the lacteals.D It produces lipase to digest fats. [1]

1. (a) Name the type of human tooth used for:(i) biting off pieces of food(ii) grinding and chewing food [2]
2. (b) Explain how chewing food helps chemical digestion. [2]

1. (a) State where bile is made and where it is stored. [2]
2. (b) Explain two ways in which bile helps the digestion of fats in the small intestine. [4]

1. (a) Describe how the stomach carries out physical digestion. [2]
2. (b) A cube of boiled potato with sides of 1 cm is cut into 8 equal cubes, each with sides of 0.5 cm. Calculate the total surface area before and after cutting. [2]
3. (c) Use your answer to (b) to explain why physical digestion speeds up chemical digestion. [1]

1. (a) A patient has her gall bladder removed. Her liver continues to make bile, which now trickles slowly and continuously into the duodenum. Explain why the doctor advises her to avoid large fatty meals. [3]

A student investigates the effect of bile salts on fat digestion. Two test-tubes each contain 5 cm³ of vegetable oil mixed with 5 cm³ of a dilute alkaline solution containing an indicator. Tube A also has 1 cm³ of bile salt solution; tube B has 1 cm³ of distilled water. Lipase is added to both tubes at 35 °C and the time for the indicator to change colour (showing a fall in pH) is recorded.tube A (with bile salts): 4 mintube B (without bile salts): 11 min

1. (a) Calculate the percentage decrease in time when bile salts are present. Give your answer to two significant figures. [2]
2. (b) Explain why the reaction is faster in tube A. [2]
3. (c) Explain why 1 cm³ of distilled water was added to tube B. [1]

1. (a) Which row correctly matches a nutrient with the disease caused by its deficiency?A vitamin C – ricketsB vitamin D – scurvyC vitamin D – ricketsD iron – scurvy [1]

1. (a) State what is meant by a balanced diet. [2]
2. (b) State two reasons why the body needs water. [2]

1. (a) A hostel student eats mostly white rice and bread with very little fruit, vegetables or meat. Suggest two nutrients that may be lacking in this diet and state a good source of each. [2]
2. (b) Explain why the body needs (i) iron and (ii) dietary fibre. [2]

1. (a) 100 g of guava contains 228 mg of vitamin C. A teenager needs 65 mg of vitamin C each day. Calculate the mass of guava, in g, that provides the daily need. Give your answer to two significant figures. [2]
2. (b) Name the deficiency disease caused by a long-term lack of vitamin C. [1]
3. (c) Explain why rickets is more common in children who rarely go outdoors and drink little milk. [2]

1. (a) What is the term for passing out of food that has not been digested or absorbed, as faeces, through the anus?A ingestionB digestionC egestionD excretion [1]

1. (a) State one function of each organ in digestion.(i) salivary glands(ii) stomach(iii) pancreas(iv) liver(v) large intestine (colon) [5]

1. (a) Define digestion. [2]
2. (b) Write the following in the order food passes through them:ileum, stomach, rectum, oesophagus, duodenum, colon [2]

1. (a) Match each statement to one process: ingestion, digestion, absorption, assimilation or egestion.(i) amino acids are used by a muscle cell to make new proteins(ii) a child takes a bite of a samosa(iii) glucose moves from the ileum into the blood(iv) fibre leaves the body through the anus(v) starch is broken down to maltose in the mouth [5]

1. (a) A student eats a meal of rice and daal (lentils). Rice is mainly starch and daal contains much protein. Describe what happens to the starch and protein from the meal as it passes from the mouth to the end of the ileum. [6]

1. (a) Describe three features of villi that increase the rate of absorption of digested food. [3]

1. (a) Into which structure in a villus are most fatty acids and glycerol absorbed?A blood capillaryB lactealC hepatic portal veinD artery [1]

1. (a) In coeliac disease, eating gluten damages the lining of the small intestine and the villi become flattened. In one patient the absorptive surface area fell from 32 m² to 4 m². Calculate the percentage decrease in surface area. Give your answer to two significant figures. [2]
2. (b) Suggest why an untreated patient with coeliac disease may lose body mass even though they eat normally. [2]

1. (a) Define assimilation. [1]
2. (b) After absorption, glucose and amino acids travel to the liver. Describe what happens to them in the body after absorption. [4]

1. (a) State where most water is absorbed in the alimentary canal. [1]
2. (b) Each day about 9.0 dm³ of water (from food, drinks and digestive juices) enters the small intestine. The small intestine absorbs 85 % of this water. The colon absorbs 90 % of the water that reaches it.Calculate the volume of water lost in the faeces each day, in cm³. [3]